Henderson said city leaders need to show more courage in converting car lanes and street parking spaces into bike lanes, creating bike corridors that parallel those focused on cars or transit, and exempting most bike projects from the detailed environment review that slow their implementation. At the same time, he said the city needs to drastically expand Muni's capacity to give people more options and compensate for bike improvements that may make driving slower.

"If you want 20 percent bike mode share, you need 30 percent on transit," he said, noting that public transit ridership in San Francisco is now about 17 percent, far less than in the great bike cities of Amsterdam and Copenhagen, which made a commitment to reducing reliance on the automobile starting in the 1970s. "It's like a puzzle."

BARRIERS AND BACKLASH

The kind of active urban planning that Henderson advocates would be anathema to many San Franciscans, particularly people like Rob Anderson, the blogger and activist who sued San Francisco over the lack of studies supporting its Bike Plan and created a four-year court injunction against bike projects that just ended two years ago.

"The only way you could get to 20 percent is creating gridlock in San Francisco. I don't think it's going to happen. City Hall is adopting a slogan as transportation policy," he told us. "It's a statement of pro-bike, anti-car principle, but it's not a realistic transportation policy."

Anderson considers bicycles to be dangerous toys that will never be used by more than a small minority of city residents, believing the majority will always rely on automobiles and there will be a huge political backlash if the city continues to take space from cars for bikes or open space.

Many city officials and cycling advocates say making big gains means convincing people like Anderson that bicycles are not just a viable transportation option, but an important one to facilitate given global warming, oil wars, public health issues, and traffic congestion that will only worsen as the population increases.

"We need to help all San Franciscans see cycling as a legitimate transportation option," Chiu said. Or as Shahum put it, "It's prioritizing space for biking, walking, and transit over driving."

Shahum said the city's political leaders seem to get it, but she doesn't feel the same sense of urgency from the city's planners.

"I feel like the bureaucracy needs to get on board. We have strong political support and the public support is growing," Shahum said. "We've set ambitious, worthwhile, and I think achievable goals, yet nobody is holding the city accountable....It can't just be a political platitude, it needs to be an actual plan with measureables and people held accountable."

She cited studies showing that the most bike-friendly cities in the U.S. are spending between $8 million and $40 million a year on bike infrastructure and education programs, "but San Francisco is spending more like $2-3 million, which is peanuts...San Francisco has got to start putting its money where its mouth is to improve biking numbers."

It's cheap and easy to stripe new bike lanes. "It's one of the best investments we can make in terms of mode share," Reiskin said. That makes cycling advocates question the city's true commitment to goals like the 2020 policy. "We will need more investment," Chiu said, "but compared to other modes of transportation, it is far cheaper per mile."

POLITICAL WILL

So why then has San Francisco slipped back into a slow pace for doing bike projects following a year of rapid improvements after the bike injunction was lifted? And why does the city set arbitrary goals that it doesn't know how to meet? The answer seems to lie at the intersection of the political and the practical.